Other Liabilities and Deferred Revenue (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Accounts Payable and Accrued Liabilities, Current [Abstract]
Dealer and dealers’ customer allowances and claims	$ 10,958	$ 13,113
Deferred revenue	2,137	2,091
Employee benefit plans	1,434	1,857
Accrued interest	1,186	1,128
OPEB (a)	329	332
Pension (a)	186	185
Operating lease liabilities	331	367
Other	3,732	3,914
Total current other liabilities and deferred revenue	20,293	22,987
Accounts Payable and Accrued Liabilities, Noncurrent [Abstract]
Pension (a)	9,718	9,878
OPEB (a)	5,684	5,740
Dealer and dealers’ customer allowances and claims	3,366	1,921
Deferred revenue	4,374	4,191
Operating lease liabilities	955	1,047
Employee benefit plans	1,125	1,104
Other	1,604	1,443
Total non-current other liabilities and deferred revenue	26,826	25,324
Net pension assets	$ 4,100	$ 3,200